1. Field of the Invention
The present invention relates to a vehicle mirror device.
2. Description of the Related Art
In conventional vehicle mirror devices used for, for example, power retractable side mirrors, when a mirror is retracted to a retracted position, a driving motor is locked. When supplied with current, the driving motor is driven to rotate even if it is being locked. As a result, the driving motor may be damaged. Therefore, there is a need of a technology for cutting off current supply to the driving motor immediately when the driving motor is locked.
For example, a conventional vehicle mirror device disclosed in Japanese Patent Application Laid-open No. 2005-306277 includes a motor-control circuit for controlling a motor for changing a position of a vehicle side mirror. The conventional motor-control circuit includes a ripple-current detecting unit, a determining unit, and a switching unit. The ripple-current detecting unit detects ripples in drive current supplied to the motor at regular intervals corresponding to the number of rotations of a rotor of the motor. The determining unit determines whether the rotor is rotating based on a result of the detection obtained by the ripple-current detecting unit. If the rotor is not rotating, the switching unit cuts off the drive current supplied to the motor.